1. Field of the Invention
This invention relates to a machine having apparatus for splining thin-walled sleeves of power transmission members.
2. Description of the Prior Art
U.S. Pat. Nos. 3,982,415; 4,028,922; and 4,045,988, all of which are assigned to the assignee of the present invention, disclose machine splining apparatus capable of forming splines in thin-walled sleeves of power transmission members. Clutches of vehicle automatic transmissions include hubs with thin-walled sleeves that must be splined in order to rotatably couple the hubs to stacked clutch discs. It is important that the splines formed are uniform in size, spacing, and shape and that the sleeve in which the splines are formed is not distorted from a round condition during the splining. With the apparatus disclosed by these prior patents, it is possible to roll the splines with the member mounted on a toothed mandrel between a pair of toothed dies on opposite sides on the mandrel. Meshing of the die mandrel teeth with the power transmission sleeve located therebetween forms the splines without excessive work hardening of the metal material.
Prior to the introduction of the spline rolling process discussed above, impact splining was the only practical way to form splines on thin-walled power transmission members such as clutch hubs. This impact splining is performed by mounting the clutch hub on a mandrel between two hammer-like dies located in a 180.degree. opposed relationship to each other. Simultaneous rapid movement of the disc toward each other bangs the clutch hub sleeves against the mandrel to form the splines. A number of strokes are performed to form each spline, proceeding from an end wall at one partially closed end of the sleeve toward an open end of the hub. After each spline is formed, the mandrel is rotated slightly and the next pair of adjacent splines are then formed. After one half of a revolution of the mandrel, the clutch hub is completely splined and can be removed from the mandrel. The splines formed by this process become work hardened during the impacting and are thus more brittle and less tough than the metal material prior to the splining. Also, axial deformation of the sleeve during the impact splining distorts the flatness of the hub end wall where the hub is usually seated for mounting during use. Also, the time required to completely spline a clutch hub with this impacting operation is considerably longer than that required with the rolling process described above. Of course, it is desirable to decrease the time for splining each hub and the amount of labor involved in order to reduce the per unit cost.